Three dimensional (3D) cell structures are important as they can mimic cell behaviors in vivo, more closely than a 2D cell culture. For example, 3D in vitro tissue models with high fidelity to in vivo tissues have important applications in tissue engineering and pathological model development, and can be used to study and test effects and mechanisms of potential therapeutic agents.
A difficulty in conventional techniques of forming 3D cell cultures is to provide efficient transportation of matter, such as a cell culturing medium, through the inner regions of 3D cell structures. As transportation of matter through a cell structure is typically by perfusion, it is more difficult to transport matter through the cell structure when the cell structure has a larger volume. In some conventional techniques, to form micro-scale cell structures, cells are encapsulated in an extra-cellular support, such as in a hydrogel or a thin layer of matrix which provides a 3D extra-cellular matrix (ECM) support for the cell structure. This extra-cellular support forms a barrier which limits transportation of matter to the cells.